Hairs on Honey Bees Essential for Pollen Removal

By Rideeta Raquib ’19

Figure 1. Bees grooming pollen with bristle-structures on legs.

Diverse flowering plants evolved during the Cretaceous and Paleogene Periods, nearly 140 to 23 million years ago, and they adapted pollinating insects for better dispersal. Several insect orders that were attracted to flowers and nectar, such as Coleoptera or Diptera became abundant as well. Although the grooming of insects has been prominent over many years, quantitative analysis on the subject is recent. Professor Guillermo J. Amador from Georgia Tech and his team of researchers analyzed the grooming mechanism of the honey bee, Apis mellifera, and pollenkitt, a sticky, thick fluid on pollen grain surfaces.

Apis mellifera purposely covers itself in pollen and transfers it to their hind legs to transport it to their hives. In this particular experiment, a honey bee was coated in pollen grains, held by a thin wire attached dorsally to the abdomen, positioned under a uniform backlight and above a transparent dish. A camcorder recorded the grooming of the honey bee, in order to determine how many swipes and frequency of swipes were required to clean the eyes. In order to test the effectiveness of pollenkitt, the pollen was also washed and centrifuged to extract the fluid. Bristle or hair length and spacing were also measured.

Pollen from the eyes and antennae were cleaned within 10 to 20 swipes of bristles. Swipes tended to move in the dorsal-ventral direction. The eye-cleaning movements took approximately 120 ms. In terms of pollenkitt and how it affects the amount of pollen removed, fresh pollen was removed at a rate of approximately 140 particles per swipe. The washed pollen removal rate was drastically lower, which was about two particles per swipe.

Overall, this study provides an insight on the dynamics of pollination and evolution. The hairiness of the bristles, geometry of the hair arrays, as well as the hair spacing plays a crucial role in removing pollen. Studies such as this one will hopefully enable scientists to create artificial pollinators and increase dispersal among plants to facilitate a steady ecology. The observations in this study could be further utilized in research regarding removal of pollen from human surfaces and clothing.